At present, the health industry is focused on providing more effective ways for patients to have more control over their own medication. One such way of providing more control to patients is to allow patients to self-medicate parenteraly drugs that cannot be delivered in other less invasive ways (such as orally). Self medication may be in the form of a syringe (as with diabetics who regularly self-inject insulin) or other drug delivery devices having an infusion mechanism and needle for penetrating the skin.
One such drug delivery device is disclosed in U.S. Pat. No. 5,527,288, which is incorporated herein by reference, for an intradermal drug delivery device and method for intradermal delivery of drugs. Such a device includes a housing, a drug reservoir, an electrolytic cell and a needle. When activated, the electrolytic cell generates a gas which presses against the reservoir and causes the drug to move out of the reservoir, through the needle and into the patient.
In some cases, these devices are intended to be packaged with the reservoir being empty and sterilised separately from the drug. Sterilisation of the drug itself with the drug delivery device is usually not desired because the sterilisation techniques used today for drug delivery devices may affect the drug's potency or otherwise adversely affect the drug itself. Thus, it is desirable to sterilise the drug delivery device and drug cartridge separately.
Sterilisation of empty drug delivery devices often occur in the packaging. Where the drug delivery device is provided with a filled drug cartridge, it is preferred that the drug delivery device be sterilised in its packaging, then the filled, sterilised drug cartridge is added to the drug delivery kit (the kit containing a drug delivery device, a filled drug cartridge and related packaging). The term "drug cartridge" herein refers to a drug container having a stopper, or plunger (typically made of natural or synthetic rubber) to seal the contents thereof.
When the drug delivery device and related packaging are sterilised separately from the drug cartridge, a problem arises in placing the drug cartridge in the kit without compromising the sterility of the device or cartridge, while enabling the device and cartridge to be packaged as a kit. Moreover, if the cartridge is packaged with the kit, there must be a way to incorporate the cartridge within the kit to prevent tampering.
With respect to drug stored in a cartridge, there is an additional packaging problem with maintaining sterility of the outer surface of the plunger when the drug is to be withdrawn from the cartridge for use. In the past, a drug delivery device was filled with drug by means of an Ogle style injection system. Such a system uses a shell cartridge having a plunger and a protective cap. The protective cap was typically applied to the top of the cartridge. This cap maintained the sterility of the outer surface of the plunger before use. However, the use of a protective cap is impractical in that it requires the application of the protective cap in the sterile environment. Such a process is time consuming and requires specialized production equipment, and as a result is expensive. Thus, there is a need for a way of maintaining the sterility of the outer surface of a drug cartridge plunger that is compatible with existing high speed cartridge-filling equipment.
In addition to the other problems associated with prior art drug delivery kits, the use of syringes to transfer drug to a drug delivery device is inherently dangerous. An exposed hypodermic needle may cause injury if the user or caregiver is accidentally pricked by the needle. Furthermore, contact with the needle by an unskilled worker could result in microbial contamination of the drug which may lead to infection.
There are at present improved drug transfer systems to reduce the risk of injury and infection caused by filling a drug delivery device with a standard syringe. Such filling systems and methods directly transfer the drug from a standard drug cartridge to the drug delivery device without exposing the patient or caregiver to any needles. One such improved filling system is disclosed in applicant's copending application filed May 6, 1997, which is incorporated herein by reference.
Such improved filling system transfers drug from a drug cartridge to a drug delivery device. A standard drug cartridge seals the drug within a drug container by means of a solid rubber plunger. The improved filling systems require a uniquely shaped rubber plunger to enable the needle used in the drug transfer to penetrate the cartridge without being exposed to the user/caregiver when the transfer mechanism is removed upon completion of the filling process.
In addition, as with prior art drug transfer systems, the sterility of the outer surface of the plunger must be maintained. This posed a difficult problem in using existing production line equipment to maintain the sterility of the outer surface of the plunger while utilising existing production line equipment to accomplish this task. As set forth in more detail above, prior art drug cartridges use a protective cap placed on the top of the drug cartridge. This method is costly and slow as it must be as an additional step after the insertion of the plunger into the drug container but must be done in a sterile environment to maintain sterility of the outer surface of the plunger until the cap is in place. Such a method required significant manual labour or use of low speed production equipment. In addition, the present filling lines leave a certain volume of air in the cartridge which is an unwanted commodity when the drug is being transferred. Until now, there has been no means for maintaining the sterility of the outer surface of a plunger on a drug cartridge by use of existing, high speed production equipment, while leaving no air between the plunger and sterility maintenance means.
Thus, there is a need to effectively assemble a drug delivery kit having a drug cartridge and a drug delivery device after the device has been sterilised.
There is a further need to provide an improved method of packaging a filled drug cartridge with a drug delivery device without subjecting the drug to the same sterilisation process as that of the device.
There is a further need to assemble a sterilised drug delivery device and a drug cartridge as a drug delivery kit while preventing tampering and/or contamination.
There is yet a further need to provide an improved method for maintaining sterility of the outer surface of the plunger of a drug cartridge prior to transfer of the drug to the drug delivery device.
There is still a further need to provide a method of assembling an improved drug cartridge that is tamper proof and that utilises existing production equipment in the assembly.